Development: a dynamic process that begins with conception and ends with death. Developmental psychology deals with the changes that occur during the course of a human life. In this article, we are going to discuss developmental processes and primary/secondary socialization as well as present the psychosexual theories of Freud and Erikson. With this, you will be optimally prepared for tricky questions about developmental psychology in your medical exams.

00:01
Okay. So let’s take a look
at what’s in our environmentand what will influence
our genetic expressions.
00:06
So genetically based behavioral
variation in a natural populationis influenced by three things.
00:10
One, the environment.
00:11
That, we’ve discussed.
00:13
The second is experiences.
00:15
So what were experiences that are
experiences that we’ve had in the pastwill actually have an impact
on our behavioral variation.
00:22
And the third really
important factor is social,I would even lump in cultural factors
into shaping these genetic changes.
00:31
Okay. Let’s look at human
physiological development.
00:35
How do we grow over time?Right down to the point where we’re
just a little sperm swimming aroundand we make that
initial connection,we start to grow, divide, and become the
ultimate super happy baby that comes out.
00:46
So at conception, the female has
an ovum and the male has a sperm,so the ovum would refer to the egg, and
the gametes fuse to form a zygote.
00:57
The zygote then contains
all the genetic materialit's going to need to develop into a human.
01:01
So that’s where you’re getting the genetic
information from your mom and your dad.
01:05
So during the prenatal stage,development is influenced by
genetic and environmental factors.
01:10
So the genetic is pretty
straightforward, right?You’re getting the genetic
information from your folks,but the environmental
factors play a huge role.
01:18
This can include a lot
of different things.
01:20
This can include the actual local
micro environment that you’re in,so what the mother is consuming,
smoking, drinking, drugs, what she eats,as well as the state
that she’s in.
01:31
So if your mother is completely stressed
and has continued to stay stressed,this might influence
that environment.
01:38
So, a lot of different things to consider.
01:40
And then outside of that
we even look at what aresome of the environmental
environmental factors,so the air that we have, the toxins in the
air, in our food, our water, our soil.
01:50
All of these things can have a
huge impact upon development.
01:56
Now, while you’re in there and
you’re growing and developingand turning into that amazing baby,you’re separated by something
called the placenta.
02:05
So the placenta transfers
nutrients and oxygen to the fetusand takes away garbage
waste and carbon dioxide.
02:11
So it’s this kind of a
protective shell, if you’d like,and it has this really important process,and all of this is done through
the exchange of blood.
02:21
So the placenta is very much connected,interconnected with the
blood supply of the mother.
02:27
So if you look at the image
here you’ll notice the redand you’ll notice the blue and
the intertwining of everything.
02:33
That are the blood vessels of the growing
and developing fetus in the placentaand the mother.
02:40
So high interconnectivity and
allows for this exchange.
02:43
Now, a lot of people misconceive
that name of placental barrierand they believe that it’s something that’skeeping all bad things
out and all toxins out,but we now understand or we have
understood for quite some time nowthat the placental barrier
actually is not a barrier at all.
03:01
It’s more of a geographical
divide really if anything,and whatever the mother consumes,anything that enters her blood -- alcohol,
drugs, caffeine, nicotine, heroin --anything she’s consuming
that enters the bloodis exchanged with the
blood of the fetus.
03:17
So there’s no barrier,
there’s no protection.
03:19
Whatever the mother is experiencing,
the child is experiencingand this leads back to our
point of environment.
03:24
So whatever environment she’s creating for
the child will impact the development.
03:28
So whatever she consumes is shared
by the child, the unborn child.
03:34
Okay. So as a baby is born and develops,
we have different stages of development,and now we’re going to look
at the motor development.
03:40
So stage one is called
reflexive movementsand this is just a very primitive Eevee
like little animal-like movementswhere the baby just kind of,
without real obvious control,is just kind of doing these little
wailing of the arms and legs.
03:53
So this involuntary movement
is used to initiateand get the whole process of the
neuromuscular system intact.
04:02
You do things like the palmar
grasp where, you know,you can put your finger or
something in front of thebaby and just instinctively
will go and grab that.
04:09
So again, that’s the mind teaching
itself these complex movementsas I need to go here, I need to
grab this thing and squeeze it.
04:16
Reflexes and learning to inhibit
the reflexes begin to develop.
04:21
So the child starts to learn reflexes
and learning to inhibit other reflexes,so things like those involuntary movements,
it learns to maybe control some of those.
04:30
So the baby starts to
develop and understandsit’s not okay to just
constantly be moving your arms.
04:36
You want to have your arms sort of at restand you want to initiate
movement as requiredand that needs to happen
by you sort of turning offsome of these
involuntary movements.
04:45
And we get to rudimentary movement.
04:46
This is where you find your
first voluntary movements --crawling, walking, grabbing
a toy, grabbing a spoon --these are first coordinated movements,and this is dictated by genetics.
04:56
So this is innate
or preprogrammed.
04:58
This isn’t something that
they typically learnso, you know, a child comes out
and that they just by themselvesstart to try to crawl,
walk, grab things.
05:06
You’re not sitting there,
“Okay, little baby,I know you don’t understand me or English
but this is how you grab a ball.”They don’t really get that.
05:13
And then stage three is
fundamental movementand this is now they’ve gotten a little bit
older or around two to seven years oldand the child learns to manipulate
their body through actions.
05:20
Now they’re really starting to get their
body to understand coordinated movement.
05:24
They’re much more coordinated and less
clumsy and not falling all the time,and it’s highly influenced
by the environment.
05:30
So the more you’re engaged with the
child, the more they’re playing,the more they’re
interacting with others,so social interaction is extremely huge
in developing fundamental movement.
05:40
Next we get to specialized movement
and now we’re getting intosort of the adolescent years.
05:45
We learn to combine fundamental movements
and apply them to specific tasks.
05:49
So, there’s a transitional substage
where a combination of movements occur,and the application
stage where consciousdecision to apply skills
to specific activities.
05:57
So there is some learning involved
and there’s some application,and this is where you can see
that a small child doesn’thave the cognitive abilities
to really make that connectionand as you get older, a little bit smarter
you’re able to get into this stage.
06:09
And then the final stage is
that lifelong application stageis the catchall for sort
of adolescents onwardsand this is where you really refine your
movements and you get much much better,and this goes more to the learning
style of behavior versus the innate.
06:25
So adolescence is a transitional period
between childhood and adulthood,I think we all understand that,and I think what some of the important
parts are what happens to the brain.
06:35
So we know that in the
brain during thisdevelopmental phase you
have cell proliferation.
06:40
So, especially, and what that refers to iscell development within the prefrontal
lobes and the limbic system,two systems that we’ve talked about
quite a bit in these courses.
06:50
Prefrontal cortex, prefrontal lobesdeal with executive function,
emotion, reasoning, behavior.
06:57
Limbic system is involved
with the arousal activation,reinforcing behaviors with the dopamine
release or the dopamine reward pathway.
07:05
So kind of stuff that’s really,
really important as you get olderand you start to develop,
especially at that adolescent age.
07:10
You also get to this process
of synaptic pruningand this, like the name implies,you consider pruning a plant or
cutting dead leaves and branches offand that’s exactly what happens,is initially we’re actually
born with a sea of connectionsbut they’re not all necessary.
07:26
And so your brain realizes
that this networkhas not fired much versus this
one which is firing a lot,so I don’t really need a lot of
those unnecessary connections,and so it actually goes
in and removes them.
07:39
So it does it through a process
called atrophy or pruningwhere they kind of descend and
those connections pull back.
07:45
And there are some really cool videos
you can catch online or read in booksand they show the
process of attachment.
07:52
So it’s going to show a neuron sending out
some of its dendrite to make a synapseand over time because
there’s no stimulationthere it actually withdraws
or shrinks into nothingor it goes back into
being a little nub.
08:04
So really, really kind of cool stuff.
08:06
And then the last thing that happens in
adolescence is the process of myelinationand you remember at the top
of this earlier modulewe talked about synaptic transmission
and salutatory conductionand how myelination increases
the conduction speed.
08:19
And so we understand that in adolescence
the degree of myelination increasesand this strengthens
synaptic connectionsand it improves transmission of
the electric chemical signal.
08:32
So this covers a
lot of informationand at this point I
hope you understandthe organization of the
central nervous system,we understand the synaptic transmission,and we understand some of the
factors that modulate our behavior.

About the Lecture

The lecture Human Physiological Development – Biological Bases of Behavior (PSY, BIO) by Tarry Ahuja, MD is from the course Individual Influences on Behavior. It contains the following chapters:

Human Physiological Developtment - Prenatal Development (PSY, BIO)

Human Physiological Developtment - Motor Development (PSY, BIO)

Included Quiz Questions

Which of the following is a biological behavior-influencing activity or factor?

Walking

Drugs

Teachers

Family separation

Access to education

Which of the following is a primitive, involuntary movement that primes the neuromuscular system in infancy?

Palmar grasp

Biceps jerk

Crawling

Walking

Knee reflex

Which of the following occurs during phase 2 of motor development?

Crawling

Postural reflex

Babinski's reflex

Tying shoelaces

Dancing

How old would a child in the fundamental motor development phase likely be?

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